The manufacture of electronic components and devices involves many processes, or steps, to produce an acceptable final product. Examples of electronic devices and components include, but are not limited to, integrated circuits (ICs), compact disks (CDs), thin film heads (TFHs), and related optoelectronic devices. The processes involved in making these devices and components are for example, but not limited to, annealing, oxidation, recrystallization, ultraviolet (UV) curing, surface conditioning, photo-assisted decomposition and etching, bacteria removal, and electrochemical decomposition. Many of these, especially photolithography, leave behind residues or resist films that must be removed without damaging the device or component being fabricated. Failure to remove these residues may produce results which range from degraded performance of the end product to complete failure.
Surface cleaning during various manufacturing processes is a major component of cost that needs to be minimized. As used herein, surface cleaning broadly includes the removal of films such as photoresist, post-etch residues, and particle removal. Photoresist and organic residue removal is the single largest cleaning application with the most urgent problems in need of solving. Surface cleaning for the removal of photoresist films and organic residues in the IC, CD, TFH, and opto-electronic fields involves the use of many corrosive and toxic wet chemicals, solvents, and large volumes of deionized water. The equipment to deliver these chemicals in the IC industry is complex, expensive, and occupies significant and costly floor space.
Typical cleaning equipment for an IC fabrication facility (IC ‘fab’) includes plasma ashers, wet benches, and dryers. These contribute to high initial capital costs. Additional facility costs are added, including floor space, plumbing for gases and air control, waste treatment and disposal. Lastly, cost of ownership (CoO) expenses, including spare parts, maintenance, and labor, is added. Wet chemicals, solvents, and deionized water may be used in conjunction with plasma ashers, wet benches, and dryers (generally wet removal techniques) for surface cleaning. The equipment required to deliver, recapture, and process these chemicals is expensive and occupies costly floor space in the manufacturing area. In addition to high equipment and chemical costs, these cleaning techniques often produce unwanted by-products that are considered hazardous and thus may have high disposal costs associated therewith. The most significant cost in wafer cleaning is that related to ultrapure water. This is a primary reason for needing a dry removal method. Wet removal techniques may further damage the delicate and intricate surfaces of the manufactured products because of the corrosive and/or abrasive nature of the cleaning media.
A second typical technique for surface cleaning may be referred to as dry removal techniques. As the name implies, dry removal techniques generally rely on non-liquid agents to perform surface cleaning. One dry removal technique employs an excimer laser operating in conjunction with a gas, such as fluorine. For example, the laser may be used to focus a beam of energy on a silicon wafer having photoresist films thereon. Additionally, a gas, such as fluorine, may be directed to an area around the beam to facilitate a reaction between the optical energy and the photoresists. Many of the dry removal techniques used in the art may fail to sufficiently clean a surface, may take a long time to remove adequate quantities of undesired products such as ion implanted resist or contaminants, may be difficult to operate, may be costly to operate, may damage the surface of the manufactured item, may require wet cleaning to remove carbon-based residues generated by the dry removal technique, may generate hazardous materials or substances and may require gases that are harmful to the environment if not handled and/or processed safely.
What is needed is a dry method or technique for removing unwanted contaminants or resist films from the surface of a substrate and which does not require or generate hazardous gases, liquids, or compounds. Furthermore, the technique should not require sophisticated and expensive handling, control, or cleaning waste product removal/processing apparatus. Further, the method should minimize or avoid damaging the substrate being cleaned to avoid any degradation of performance.